Remote control apparatus



.Eufly 16, 1940, G. w. BAUGHMAN REMOTE CONTROL APPARATUS Fi'led Feb. 17,1939 2 Sheets-Sheet l Q Q E Juiy 16, 1940, e. w. BAUGHMAN REMOTE CONTROLAPPARATUS 2 Sheets-Sheet 2 Filed Feb. 17, 1939 M w -L mwm w mw PatentedJuly 16, 1940 UNITED STATES 2,208,446 REMOTE CONTROL APPARATUS George W.Baughrnan, Pittsburgh, Pa, assignor to The Union Switch & SignalCompany,

Swissvale, Pa., a corporation of Pennsylvania Application February 17,1929, Serial No. 256,976

16 Claims.

My invention relates generally to remote control systems, and moreparticularly to the communication or line circuits for such systems.

My invention is particularly adapted for though in no manner limited tocentralized trafflc controlling systems for railroads in which a traindispatchers ofiice'or other suitable point of control is connected witha plurality of field statlons by line wires, over which code signals aretransmitted at times for controlling selected devices at the stations,and at other times for indicating the condition of station devices atthe oiiice. The code signals may be of any suitable character, but inthe illustrative embodiments 1 which I have chosen, the code signals areformed by interrupting the current from a battery located at the ofliceend of the line circuit.

My invention may advantageously be applied, for example, to acentralized trafiic control system such as the one disclosed in thepending United States application, Serial No. 600, 786, filed March 23,1932 by Lloyd V. Lewis, for Remote control system, which correspondswith British Patent No. 415,787, issued September 3,

One object of my invention is to provide additional communicationchannels over the line wires of centralized traflic control system, theadditional channels being suitable, for example, either for telephonecommunication or for code signaling, or for both purposes. A specificobject of my invention is to provide telephone communication ofunimpaired quality over a line circuit which is also used for whichincludes line relays at way stations.

a large number of A further object of my invention is to extend thelength of territory and the number of stations which may be controlledby a centralized traffic control system. In accordance with this featureof my invention the line c1rcu1t 1s sectionalized, each sectionproviding a physical circuit for the control of a large number of waystations, and the code signals transmitted between the oiiice and themore remote sections are relayed over the intervening sections by theemployment of additional channels such as those above referred to.

Other objects, purposes and features of my invention will be pointed outas the description proceeds.

I shall describe several forms of apparatus embodying my invention, andshall then point out the novel features thereof in claims.

Referring to the accompanying drawings, Fig. l. illustrates the linecircuit for a centralized traffic control system such as the onedisclosed in the patent hereinbefore referred to, which has beenmodified in accordance with one form of my invention to providesuperimposed alternatcode signaling and ing current communicationchannels. It is to be, understood that this View may be expanded toinclude additional intermediate stations, the maximum capacity of thesystem in the form illustrated in the patent being thirty-five stations.Fig. Zshows a modified form of the apparatus at an intermediate station,which is suitable for use in the system of Fig. 1. Fig. 3 illustratesv asecond modification of the intermediate station apparatus which may beused in the system of Fig. 1 when single wound line relays, asillustrated in the patent, are used, Fig. 4 illustrates one manner inwhich certain of the superimposed communication channels of the systemof Fig. 1 may be used for code signaling to provide for the control andindication of devices at a large number of additional stations locatedat a considerable distance from the control oflice. It is to beunderstoodthat in Fig. 4 the first section of the line circuit extendingfrom the ofiice to the end station 355 may include apparatus at a largenumber of intermediate stationssuch as that at station is in Fig. 1, orsuch as is shown in Fig. 2 or in Fig. 3, and that the second section ofthe line circuit extending from station 355 in Fig. i to station MS maybe similarly arranged. For simplicity, only the physical circuit for thesecond section and only one superimposed channel for each direction forthe first section is shown in Fig. 4, but it is to be understood thatadditional channels may be added as required by the provision ofsuitable well-known filtering arrangements, such, for example, as aredescribed in section 11, page 17, of the Electrical Engineer's Handbook,Vol. V, published by John Wiley 8; Sons, Inc., New York, 1936, or byother suitable means. I

Similar reference characters refer to similar parts in each or theseveral views.

The designations for the various relays disclosed herein are the same asthose for the corresponding relays of the British Patent No. 415,- 787,hereinbeiore referred to. As more fully explained in the patent, theline circuit for code signaling is normally closed and energized by aline battery 8d at the control office. As shown herein in Fig. l, theline circuit extends from battery 8!] over back contacts of atransmitter relay OT and the winding of a line relay OR at the controloffice to line wires Y and Z, thence through the winding. of a similarline relay R and back contacts of a master relay M at the first stationis to the outgoing line wires Yl and Zl, thence similarly through eachintermediate station, the circuit being completed from the incomingwires Y34 and Z34 at station S35- atthe end of the line through thewinding of the relay R and the back contacts of the relay M at thatstation. Control codes each comprising a series of time spacedimpulsesand intervals are transmitted from the office by intermittentlyenergizing the office transmitter OT, these codes being received by theoflice line relay OR, which relay controls relay CT to govern thetransmission of the impulses, and also by the line relays R whichcontrol the selective apparatus at the stations, the apparatus at eachstation being responsive to a different code. Indication codes aretransmitted from a station by energizing the corres: ponding relay M atthe transmitting station for the duration of the code, to deenergize theportion of the line circuit extending to stations more remote from theoffice, the portion extending to the oflice being completed over a backcontactof the relay T at the transmitting station and a compensatingresistor 5 of a value approximately equal to the resistance of thedisconnected line portion. Relay T is then operated intermittently totransmit a code characteristic of the station under the control of theassociated relay R, this code being received by line relay OR to operatesuitable selecting apparatus at the office. The apparatus is arranged sothat a code may be initiated bythe oifice or by any station when theline is free, and is further arranged so that no, interference occurs inthe event two or more transmitters are initiated simultaneously, theseveral codes being transmitted one at a time in a predetermined orderunder this condition as fully explained in the patent.

The line circuits shown herein differ from those of the patentbyincluding certain provisions for.

better adapting the system for use over lines which are relatively longelectrically, such, for

7 example, as a long distance cable line having confilter "station. Whenan intermediate station is transsiderable cable capacity, as disclosedin a pending Lewis application for United States Patent, Serial No.13'7,500, filed April 17, 1937, for Remote control system. Theseprovisions include the use of sensitive line relays of the biased polartype in place of ordinary neutral relays, and the provisions of meansfor discharging the energy stored in the distributed capacity of thecable when the battery ,88 is disconnected from the line, comprising ashunt including a resistor 6 which connects line Y to line Z each timethe office relayOT picks up, and a choke coil 1 at each station forsimilarly discharging the remote portion of the line when that stationis transmitting. The line circuits are further modified in accordancewith the present invention by providing the line relays with two equalwindings one of which is in series with each line wire, and byinterposing a low pass filter 8 suchas is used in the telegraph branchof the usual composite circuit, in the line circuit between the linewires Y, Z and the contacts of relay OT at the office and relay T ateach station. Such filters are highly satisfactory for this purpose,since the frequency of the code signals as usually employed is lowerthan that of the usual telegraph code signals. With these arrangements,the line wires, are rendered available for non-interfering voicefrequency communication, and a telephone circuit may be superimposedupon the code signaling line. As illustrated in Fig. l, the voicefrequency circuit normally extends from the telephone apparatus 9 at theoifice through a highpass filter indicated conventionally by thecondensers in to line wires Y, Z thence through the windings of relay Rand back contacts of relay M at each intermediate station, through asimilar ill to thetelephone apparatus 9 at the end mitting the relay Mat that station sectionalizes a remotely controlled signal.

the line for the code signaling channel, but the voice frequency channelis maintained intact under this condititon by the provision of by-passcondensers I! at each station connected across the contacts of thecorresponding relay M. Since the code signaling channel includes usuallya large number of relays in series these relays are preferably wound tohave a low resistance and inductance, which is also desirable becausethe voice frequency currents pass through these relays.

It is also desirable to select the inductance of these relays so thatthey will act in the same manner as the loading coils usedon longdistance telephone lines. A satisfactory value of loading for telephonelines is 0.175 henry per 8 miles for open wire line, and the same valueper 9000 ft. for cable. The usual value of the inductance of the linerelays in the system described as heretofore used is around 0.1 henry,and the'stations are usually located at intervals of three or fourmiles, and it is apparent that but a minor change, if any, in the relayconstants is required to adapt the relays to the purposes of the presentinvention. In order to eliminate reflection losses it is necessary thatthe loading coils be uniformly spaced. If the stations are irregularlyspaced, as is usually the case, the electrical equivalent of uniformloading may be obtained by connecting a fixed condenser as indicated atI? across the line to increase the capacity to correspond with that of anormal loading section, when the distance between stations isinsufficient, or by inserting a loading coil as indicated at l3 inseries with the line when this distance is excessive, the values of thecondensers l 2 and coils i 3 being so'chosen as to maintain a fixedratio between the line inductance and capacity per unit of distance.

It Will be seen from the foregoing that irrespective of the number ofstations, the branch of the code signaling circuit which is in use atany time contains only two filters, namely, those at its two ends, andconsequently the quality of the code transmission will not be impairedby the addition of the filters 8 and I0 and of the condensers l2 andcoils ill to even the slight extent as in the usual composite circuit inwhich the code signaling apparatus is located at the ends only. Further,the voice communication channel may be arranged to provide high qualitytransmission and may be extended from either end to a more remote pointif desired.

In centralized traffic control systems it is often desirable to providefacilities to enable the operator at the control office to communicateby telephone with the maintainer in charge of the station apparatus orwith the crew of a train held at In such cases the operator may call themaintainer to the nearest station by the transmission of a special codeassigned to that purpose, and the maintainer or a train crew maycommunicate with the operator by connecting suitable telephoneapparatus, not shown, to the line by means of a jack It provided .ateach intermediate station. A loud speaker is ployed in a well-knownmanner to provide a plurality of code signaling channels each employing.a different frequency as hereinbefore mentioned, or higher frequenciesmay be used to provide carrier-current transmission channels.

In such cases it may be preferable to omit the loading of the line bythe series line relays as hereinbefore described. When this is the case,the apparatus at each intermediate station may be arranged in accordancewith Fig. 2, which differs from the corresponding portion of Fig. 1 inthat a high-pass filter shown as the condensers H bridges the winding ofthe relay R as well as the contacts of relay M. This permits highervalues of alternating current to be used without causing vibration orchattering of the direct current relays at the intermediate stations.

My invention may also be applied to installations of the system of thepatent hereinbefore mentioned which employ line relays of the ordinaryneutral type. One manner in which this is accomplished is shown in Fig.3, which shows apparatus for two successive stations which'may beincluded in the line circuit of Fig. 1. This arrangement differs fromFig. 2 in that the line relays at alternate stations are included inline Y while the remaining line relays are included in line Z, so as tobalance the characteristics of the two line wires as closely as ispracticable. Since the operation of the system when the modifications ofFig. 2 or Fig. 3 are employed is generally similar to that alreadydescribed, it is believed that it will be'readily understood withoutfurther description.

In some installations the number of stations or the density of trafiicis too great to permit the control of the apparatus at all the stationsover a single line circuit. In such cases it has been the practice toemploy two wires extending over a portion of the territory for thecontrol of the apparatus at the nearby stations, and two other wiresextending over the entire length of the territory for the control of theremainder.

In Fig. 4 is shown an arrangement whereby the necessity for theadditional line wires is obviated. In this view a single pair of linewires provides two circuits in end to end relation, including a firstcircuit extending from the office to an end station 356, and the secondfrom that station to a more remote end station 108. Each physicalcircuit provides a code signaling channel as hereinbefore described,that is, stations IS to 35S may be controlled over the first circuit,and the additional stations 36S to His over the second. The firstcircuit is arranged to provide superimposed alternating current channelsas in Fig. 1 and the intermediate stations, not shown, may be arrangedas already described in connection with Figs. 2 and 3. The'secondcircuit may be similarly arranged, but, as shown, the superimposedcircuits are omitted since they are not required when the line has buttwo sections as shown. The intermediate stations which are controlledover the second line circuit are not shown, since these may be arrangedas shown in the patent. The office is provided with two coding units,the one for the first line circuit having a transmitter GPA and a linerelay ORA arranged as shown in the British patent hereinbefore referredto and described in connection with Fig. 1. The transmitter OTB for thesecond unit has a normally open front contact which is employed todeliver control code signals from a source of alternating currentindicated by the terminals BXl and CK! through a tuned circuit to ahybrid coil l5, the secondary windings of which deliver the coderespectively through condensers ill to lines Y and Z, and to a balancingnetwork comprising the artificial line AL. The alternating currentsignals passing over the line to sections Y34 andZ34 at the end station35S pass through the-condensers l0 and one-half of the hybrid coil I5atthat station to thetuned' circuit comprising the condenser I6' and thecoil l1 and are rectified by the rectifier unit l8 to operate thetransmitter repeating relay OTP, which relay delivers the, code to thesecond line circuit-in the usual manner. It is to be understood that avacuum tube amplifier may be included in this circuit when required.

Code signals in the second line circuit due to the operation of relayOTP or to that of a relay T at any one of the stations 36S to 10$operate the line relay ORB, which relay in a manner similar to thatalready described for relay OTB transmits an alternating current codeover the first line circuit from an alternating current source of afrequency preferably different from that transmitted by relay OTB, theterminals of this alternating current source being designated BXZ andOX2. Codes of this second frequency operate the relay ORP at the officewhich replaces the usual relay OR in the control of the second ofiicecoding unit. It will be noted that the alternating current channels arenormally open so that the codes are reversed, and the absence ofalternating current corresponds to the line-closed condition, and thealternating current impulses correspond to the line-open condition ofthe battery code line. Consequently the connections to the contacts ofrelays OTB and OR? are reversed with respect to the correspondingconnections of other similar relays.

In the system of the patent each relay OT or T is made somewhat slowacting to time the impulses, and its repeated operation is governed bythe associated line relay OR or R. In transmitting control codes overthe second line circuit the control of relay OTB by relay O-RP isdependent upon the operation of two additional relays OTP and ORB,consequently relay OTB is made quicker acting than the othertransmitting relays in order to secure approximately the same timing, sothat the codes transmitted over the two line circuits will have similarcharacteristics and permit the use of interchangeable station apparatus.

It will be apparent that the method of control illustrated in Fig. 4 maybe further extended to include a third section, in which case two pairsof alternating current channels with selective filtering arrangementsare provided over the first section, one for the control of the secondsection, and the other extending also over the second section for thecontrol of the third section. Since the number of channels renderedavailable by the use of filters is more than any installation is likelyto require, it is evident that only two line wires will be required evenin the case of extremely large installations involving heavy traffic.

Although I have herein shown and described but a few forms of apparatusembodying by invention, it is understood that various changes andmodifications may be made within the scope of the appended claimsWithout departing from the spirit and scope of my invention.

Having thus described by invention, what I claimis:

1. In a remote control system, an ofiice and a plurality of stationsconnected by two line wires, a code signaling circuit including saidline wires, a source of direct current, and a line relay at the ofliceand at each station, in series; means for repeatedly interrupting saidsignaling circuit to operate said line relays in accordance withdifferent codes, a voice frequency communication circuit including saidline wires, means for signaling over said voice frequency circuit, andmeans for preventing interference between the two circuits comprisinglow-pass filters in the code signaling circuit at its two ends only andcondensers in the voice frequency circuit at its two ends only.

2. In a remote control system, an oflice and a plurality of stationsconnected by two line wires, a normally energized code signaling circuitincluding said line Wires, a source of direct current, and a line relayat the office and at each station, in series; means forrepeatedlyinterrupting said signaling circuit to operate said linerelays in accordance with diiferent codes, a voice frequencycommunication circuit including said line Wires and the windings of theline relays at intermediate stations, means for transmitting periodiccurrents over said voice frequency circuit, and

means comprising said line relays for loading said superimposed circuitto more efiiciently pass periodic currents of selected frequencies, thewindings for. said relays being proportioned. to have a particularinductance with reference to the distributed inductance and capacity ofsaid line wires.

3. nI a remote control system, an office and a plurality of stationsconnected by two line wires, a code signaling circuit including saidline wires, a source of direct current, and a line relay at the ofiiceand at each station, in series means for re peatedly interrupting saidsignaling circuit 7 to operate said line relays in accordance withdifferent codes, a voice frequency communication circuit includingsaid'line wires and the windings of the line relays at intermediatestations, the windings of such relays being chosen to have an inductanceof a particular value with respect to the distributed inductance andcapacity of said line wires to so load the line as to more efficientlypass a desired band of frequencies, means comprising series inductancesand shunt condensers in said line circuits for rendering the loading dueto said relays more uniform per unit of length when said intermediatestations are irregularly spaced, and means for transmitting periodiccurrents over said voice frequency circuit.

4. In a remote control system, an office and a plurality of stationsconnected by two line wires,

a code signaling circuit including said line wires, 7

a source of direct current, and a line relay at the office and at eachstation, in series, said circuit also including a low-pass filter ateach end only; means for repeatedly interrupting said signaling circuitto operate said line relays in accordance with different codes, a voicefrequency communication circuit connected through condensers to saidline wires at the ofiice and at a distant station, and means fortransmitting periodic currents over said voice frequency circuit.

5. In a remote control system, an office and a plurality of stationsconnected by two line wires, a code signaling circuit including saidline wires, a source of direct current and a line relay at the ofiiceand at each station, in series, code transmitting means at the officeeffective at times to repeatedly interrupt said signaling circuit tooperate the stationline relays in accordance with different codes, codetransmitting means at each station effective at times to open theportion of said signaling circuit extending to stations more remote fromthe office and to then repeatedly interrupt the remaining portion to,operate .the office line relay, a voice frequency communication circuitincluding the same line wires and arranged to provide communicationbetween the ofiice and any station, and means for maintaining thecontinuity of said Voice frequency circuit when a code is beingtransmitted from the oifice or from any station.

6. In a remote control system, an office and a plurality of stationsconnected by two line wires, a code signaling circuit including saidline wires, a source of direct current and a linerelay at the office andat each station, in mitting means at the'olfice effective at times torepeatedly interrupt said signaling circuit to operate the station linerelays in accordance with different codes, code transmitting means ateach station "effective at times to open the portion of said signalingcircuit extending to stations more remote from the ofiice and to thenrepeatedly interrupt the remaining portion to operate the oiiice linerelay, a voice frequency communication circuit including the same linewires and arranged to provide communication between the ofiice and anystation, a low pass filter associated with each code transmitter forpreventing the delivery of transient currents in the voice frequencyrange to the line wires by such transmitter when operating, and meansfor maintaining the series, code transcontinuity of said voice frequencycircuit when a 7. In a remote control system, an office and a pluralityof stations connected by two line wires, a code signaling circuitincluding said line wires, a source of direct current and a line relayat the office and) at each station, in series, code transmitting meansat the oilice effective at times to repeatedly interrupt said signalingcircuit to operate the station line relays in accordance with differentcodes, code transmitting means at each station effective at times toopen the portion of said signaling circuit extending to stations moreremote from the office and to then repeatedly interrupt the remainingportion to operate the office line relay, a voice frequencycommunication circuit including the same line wires and arranged toprovide communication between the office and any station, a low-passfilter associated with each code transmitter for preventing the deliveryof transient currents in the voice frequency range to the line wires bysuch transmitter when operating, and means for excluding the low-passfilter at each intermediate station from the code signaling circuitexcept when the transmitter at that station is operating.

8. In a remote control system, a single line circuit extending from acontrol office serially through a first group of stations and arrangedto provide two non-interfering two-way communication channels, a secondline circuit eX- tending from the station of the first group most remotefrom the office serially through a second group of stations and arrangedto provide a single two-way communication channel, two code transmittersand receivers at the oifice and one code transmitter and receiver ateach station, means including one ofjsaid two channels for deliveringcodes from one office transmitter to the receiver at each station of thefirst group and from the transmitter at each such station to onereceiver at the olfice, and means including the other of said twochannels and said single channel for delivering codes from the otheroifice transmitter to the receiver at each station of the second groupand from the transmitter at each station of the second group to theother receiver at the office.

9. In a remote control system, a first line circuit extending from acontrol ofiice through a first group of stations, a second line circuitextending from one of said stations through a second group of stations,two code transmitters and receivers at the ofiice and one codetransmitter and receiver at each station, means including said firstline circuit for delivering codes from one office transmitter to thereceiver at each station of the first group and from each such stationto one receiver at the office, and means including both line circuitsand the transmitter and receiver at said one station for deliveringcodes from the other office transmitter and receiver to each station ofthe second group and from the transmitter at each station of the secondgroup to the other receiver at the oifice.

10. In a remote control system, a line circuit extending from a firststation through a plurality of remote stations, a control OffilCE at apoint remote from said first station, a code transmitter and a linerelay for governing the operation of said transmitter at the controloifice, a repeating relay at said first station remotely controlled bysaid oflice transmitter for delivering codes to said line circuit, aline relay at each station responsive to said codes, and means forremotely controlling the line relay at the office in accordance with theoperation of the line relay at said first station.

11. In a remote control system, a code signaling circuit including linewires extending from a control office through a plurality of remotestations, automatic sectionalizing means at an intermediate stationeffective at times to interrupt said circuit to disconnect the controlmice frommore remote stations, an alternating current signaling circuitincluding the same line wires and extending from the office through saidintermediate station, and means effective when said sectionalizing meansis operated to include condensers in said alternating current circuit atsaid intermediate station to maintain its continuity.

12. In a remote control system, a single line circuit extending from acontrol oflice through a plurality of remote stations, means forestablishing two communication channels over said line circuitcomprising high-pass and low-pass filters connected thereto at theoffice and at a remote station, automatic sectionalizing means forinterrupting said line circuit at times at an intermediate station, andmeans effective when said sectionalizing means is operated forconnecting high-pass and low-pass filters to said line circuit at saidintermediate station to establish one communication channel between theoffice and said intermediate station and another between the ofiice anda more remote station.

13. In a remote control system, a single line circuit extending from acontrol ofii'ce serially through a first group of stations and arrangedto provide a physical circuit for two-way communication and twosuperimposed non-interfering one-way channels for communication inopposite directions, a second line circuit extending from one station ofthe first group serially through a second group of stations and arrangedto provide a second two-way communication circuit, two code transmittersand receivers at the office and one code transmitter and receiver ateach station, means incuding said physical circuit for delivering codesfrom one oflice transmitter to the receiver at each station of the firstgroup and from the transmitter at each such station to one receiver atthe ofiice, means including said one-way channels and said secondtwo-Way circuit for delivering codes from the other oflice transmitterto the receiver at each station of the second group and from thetransmitter at each station of the second group to the other receiver atthe office.

14. In a remote control system, a single line circuit extending from acontrol office to a remote station and arranged to provide twononinterfering one-way communication channels one for each direction, asecond line circuit extending from said remote station serially througha plurality of stations and arranged to provide a single two-waycommunication channel, a code transmitter and receiver at the ofiice andat each station, means including one of said two channels for deliveringcodes from the oflice transmitter to said two-way channel to control thereceiver at each station, means including said twoway channel and theother of said two one-way channels for delivering codes from thetransmitter at each station to the receiver at the office, and meanseffective when said office transmitter delivers a code over the one ofsaid two channels to said two-way channel to repeat said code back tothe office over the other of said two channels to govern the operationof said transmitter.

15. In a remote control system, a first line circuit extending from acontrol office serially through a first group of stations and'arrangedto provide a physical circuit for the transmission of codes of directcurrent impulses from said ofiice to said stations, and to also providenon-interfering superimposed channels for the transmission of othercodes from the office to one station and from said one station to theofiice', a second line circuit extending serially through a second groupof stations including said one station and arranged to provide a circuitfor the transmission of impulse codes from said one station to theremaining stations of the second group, a transmitter relay at theofiice effective to deliver said direct current impulse codes over saidphysical circuit to the stations of the first group, a secondtransmitter at the offlce effective to deliver impulse codes over one ofsaid superimposed channels to said one station, a repeating relay atsaid one station responsive to the codes delivered by said secondtransmitter for repeating such codes over said second line circuit tothe stations, of said second group, and means for repeating the codesdelivered to said second line circuit back to the office over the othersuperimposed channel to govern the operation of said second transmitter.

16. In a remote control system, a line circuit extending from a firststation through a plurality of remote stations, a source of current atsaid first station, a repeating relay at said first station fordelivering current impulses from said source to said line circuit, saidimpulses being arranged in accordance with different codes, atransmitter relay at a point remote from said first station forcontrolling said repeating relay, a line relay at each stationresponsive to the codes delivered to said line circuit, means includingthe line relay at one station for governing the operation of saidtransmitter relay, and means including the line relays at the otherstations for receiving said codes of impulses.

GEORGE W. BAUGI-IMAN.

